Camshaft adjusting devices, particularly those working hydraulically, are sufficiently well-known in the prior art. In the hydraulic camshaft adjuster there is a vane impeller, in which vanes are formed or arranged. The vanes are situated in hydraulic chambers, which are incorporated in an external rotor. The internal rotor (connected to the camshaft) can be adjusted relative to the external rotor between an ‘advanced stop’ and a ‘retarded stop’ by way of corresponding admission of hydraulic fluid to the respective side of the hydraulic chambers. The flow of hydraulic oil is here controlled by an electrically actuated directional valve.
The rotary motion of the crankshaft is generally transmitted to the external rotor via a gearwheel, which is rotationally fixed to the external rotor. In the prior art there are known solutions in which the gearwheel is embodied as a chain sprocket and is arranged at the outer circumference of the external rotor or rotationally fixed to the external rotor.
A camshaft adjusting device of generic type is described in DE 10 2004 038 695 A1. Here the drive element has a laterally attached and fixed covering element. An axial end section of the drive element or its housing in this case has a cylindrical receiving face.
The covering element is seated on the receiving face by way of a corresponding seating face. In order to afford the covering element sufficient grip on the axial end section of the drive element or its housing, a press-fit is here provided between the cylindrical receiving face and the cylindrical seating face.
DE 10 2006 039 371 A1 shows a similar solution. Here too, the camshaft adjuster has a drive element, which is rotationally fixed to the crankshaft. An output element, which is rotationally fixed to the camshaft, is rotatable relative to the drive element. The device is axially limited by a side cover at each side.
A torsion spring in the form of a flat spiral spring is also provided. A first end of the torsion spring acts on the output element. The other end of the torsion spring is fixed to the drive element. The torsion spring is here under a pre-tension, so that it can exert a torque on the output element relative to the drive element. The torsion spring serves to compensate for a friction torque, which acts on the camshaft and pushes the output element towards retarded timings. The torsion spring is further provided in order to move the output element into a basic position in which the output element can be mechanically locked to the drive element should the hydraulic medium supply to the device become insufficient.
The torsion spring is arranged in a spring compartment, which is delimited on the one hand by the side cover and on the other by the aforementioned covering element (spring cover). The covering element grips radially and axially over the side cover and is provided with a positively interlocking element.
A disadvantage of the hitherto known solutions is that although the first component and the second component, that is to say, in particular, the front or side cover of the drive element and the covering element, are cost-effective to produce, the production tolerances mean that the press-fit between the two parts, that is to say the radial compressive stress between the two cylindrical contact faces between said parts, which constitute a transverse press-fit, cannot be kept sufficiently precisely within a predefined tolerance band.